Method for orienting hydraulic fractures in multilateral horizontal wells

ABSTRACT

The method for orienting hydraulic fractures in a subterranean formation comprises injecting a first fluid into a first horizontal wellbore penetrating the subterranean formation and open to the formation in at least one specified segment and pressurizing the first fluid in the first wellbore to create a stress field around each specified segment of the first wellbore. A second pressurized fracturing particle-laden fluid is simultaneously injected into a second horizontal wellbore open to the formation in at least one specified segment and vertically spaced apart from the first wellbore for inducing fractures propagating from the specified segments of the second wellbore towards the specified pressurized segments of the first wellbore.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Russian Application No. 2015114753 filed Apr. 21, 2015, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The invention is related to hydraulic fracturing of subterranean formations for stimulation of oil and gas wells and can be applied to any type of tight or low-permeability formations (gas or oil bearing).

BACKGROUND

Hydraulic fracturing is the main method used for increasing the productive capacity of a well through creation or expansion of drains from a wellbore to oil-bearing formations. This operation is generally accomplished by injecting a highly viscous liquid (a fracturing fluid) containing a proppant into a well to pressurize the latter so as to initiate a fracture in the earth formation.

There is known a method for optimizing hydraulic fracturing by aligning wellbore perforations with the previously determined direction of fracture propagation (U.S. Pat. No. 5,318,123). This invention involves alignment of perforations produced by a variety of perforating devices with the previously determined direction of fracture propagation. That invention does not change the direction of fracture propagation, it just makes it easier to open a fracture by aligning perforations with the pre-determined direction of fracture propagation.

There is also known a method for fracturing multilateral wells disclosed in U.S. Pat. No. 8,220,547. The method presents fracturing the plurality of lateral wellbores in a single completion run by isolating sequential lateral wellbores of the plurality of lateral wellbores in descending order and delivering fracturing fluid to each sequential lateral wellbore while isolated. The method does not provide for creation of a fracture intersecting two laterals at the same time.

SUMMARY

The disclosed method provides for increased productivity of a well and high precision fracture placement due to controlled fracture initiation and propagation.

The disclosure provides a method for orienting hydraulic fractures in a subterranean formation. The method comprises injecting a first fluid into a first horizontal wellbore penetrating the subterranean formation and open to the formation in at least one specified segment and pressurizing the first fluid in the first wellbore to create a stress field around each specified segment of the first wellbore. A second pressurized fracturing particle-laden fluid is simultaneously injected into a second horizontal wellbore open to the formation in at least one specified segment and vertically spaced apart from the first wellbore for inducing fractures propagating from the specified segments of the second wellbore towards the specified pressurized segments of the first wellbore.

According to embodiments of the invention, the first and the second horizontal wellbores are lateral wellbores of a multilateral well.

The first fluid injected into the first horizontal wellbore can be a pressurized fracturing fluid or a natural gas. The second pressurized fracturing particle-laden fluid can be used as the first fluid.

The first wellbore and the second wellbore can be open to the formation though open perforation clusters or a sliding sleeves.

BRIEF DESCRIPTION OF DRAWINGS

Those skilled in the art should more fully appreciate advantages of various embodiments of the present disclosure from the following drawings:

FIG. 1 is a schematic view of two lateral wellbores penetrating a formation with an induced fracture in accordance with one embodiment of the invention:

FIG. 2 a schematic view of two different horizontal wellbores penetrating a formation with an induced fracture in accordance with another embodiment of the invention.

DETAILED DESCRIPTION

The method is based on the fact that during injection of a high pressure fracturing fluid in a wellbore, fractures occur that propagate from the wellbore in the direction of a maximal stress of the formation. The method includes creating hydraulic fractures by injecting a pressurized particle-laden fracturing fluid into one horizontal wellbore penetrating a formation and exposed to the formation in some specified segments through open perforation clusters or sliding sleeves, and by pressurizing another horizontal wellbore vertically spaced apart from the first wellbore and also open to the formation in the same number of specified segments through open perforation clusters or sliding sleeves. Thereby, the method creates fractures which propagate from the specified segments of one horizontal wellbore towards the specified pressurized segments of another horizontal wellbore. Productivity/injectivity may be controlled via hydraulic connectivity through the fractures between the two drains. Dynamic control of fracture propagation allows high precision fracture placement.

According to one embodiment of the disclosure (see FIG. 1) vertically spaced-apart lateral wellbores 1 and 2, and according to another embodiment of the disclosure (see FIG. 2) vertically spaced apart different horizontal wellbores 1 and 2, are drilled, cased, and cemented, and then connected to formation in specified segments either through perforation clusters or by means of sliding sleeves (not shown).

The wellbore 1 is used as an injector to pump a high pressure fracturing fluid containing proppant and induce and propagate at least one hydraulic fracture 3 from a segment 4 (or several segments, not shown) open to the formation. The wellbore 2 is used to pressurize a specified segment 5 or several specified segments (not shown) by filling the wellbore 2 with a fluid which can be a fracturing fluid or any natural gas and by increasing pressure. The high pressure fracturing fluid injected into the wellbore 1 can be used to pressurize the specified segment 5 of the wellbore 2.

However, pressurizing should not result in fracturing of the wellbore 2, so pressure should not exceed fracture pressure, which is determined case-by-case for specific rock properties. The pressurization is done in order to create a specific stress field shown by broken lines around each specified segment 5 of the wellbore 2 (open to formation), which would attract the hydraulic fractures 3 propagating from the wellbore 1 through the specified segments 4 of the wellbore 1 in the direction 6 of a maximal stress of the formation.

In a particular realization of the method described above (see FIG. 1), we would consider one well drilled vertically for 1000 m and then branching in two laterals drilled horizontally in parallel for 3000 m. The vertical spacing of the laterals is 100 m. The reservoir is a low permeability Achimov formation. Four perforation clusters are created in each of the laterals. Then the method described above is applied to create four fractures connecting both laterals and going from one respective perforation cluster on one lateral to another perforation cluster on another lateral. The fractures are created using YF140 fracturing fluid with 100 mesh sand. The mixture of fracturing fluid with sand is pumped to create each of the fractures at the flowrate of 8 m3/min.

Although the preceding description has been described herein with reference to particular means and embodiments, it is not intended to be limited to the particulars disclosed herein; rather it extends to all functionally equivalent structures, methods and uses, such as are within the scope of an appended claims. 

What is claimed is:
 1. A method for orienting hydraulic fractures in a subterranean formation, the method comprising: injecting a first fluid into a first horizontal wellbore that penetrates the subterranean formation and is open to the formation in at least one specified segment, pressurizing the first fluid in the first wellbore to create a stress field around each specified segment of the first wellbore, simultaneously injecting a second pressurized fracturing particle-laden fluid into a second horizontal wellbore that is vertically spaced apart from the first wellbore and is open to the formation in at least one specified segment for inducing fractures propagating from the specified segments of the second wellbore towards the pressurized specified segments of the first wellbore.
 2. The method of claim 1 wherein the first and the second wellbores are lateral wellbores of a multilateral well.
 3. The method of claim 1 wherein the second pressurized fracturing particle-laden fluid is used as the first fluid injected into the first wellbore.
 4. The method of claim 1 wherein the first fluid injected into the first wellbore is a natural gas.
 5. The method of claim 1 wherein the first wellbore is open to the formation through open perforation clusters.
 6. The method of claim 1 wherein the first wellbore is open to the formation though sliding sleeves.
 7. The method of claim 1 wherein the second wellbore is open to the formation through open perforation clusters.
 8. The method of claim 1 wherein the second wellbore is open to the formation through sliding sleeves. 